PROJECT BACKGROUND: Shared Medical Appointments (SMAs)-group sessions of Veterans with the same medical condition led by a multi-disciplinary/multi-expertise team of providers-are now being widely implemented at VA facilities nationwide. Efficacy trials have found that SMAs in VA increase access to care and improve participants' self-management, clinical, and Veteran-centered outcomes during and immediately after completion of the SMAs. Less is known about the extent to which gains achieved through SMAs are maintained over time and, if not, what additional scalable approaches can best maintain improvements in self-management and clinical outcomes. Moreover, factors influencing effective implementation of SMAs and follow-up maintenance programs in diverse settings are poorly understood. One potentially scalable approach is telephone-based peer support in which fellow Veterans provide support to each other. Because peers share similar characteristics, this approach is intrinsically culturally sensitive. Moreover, because most contacts are over the telephone, it is accessible to vulnerable patients who face obstacles to accessing clinic-based care. PROJECT OBJECTIVES: Accordingly, this mixed methods cluster randomized controlled trial will evaluate the comparative effectiveness and implementation of a novel reciprocal peer support program-the Peer to Peer Program (P2P)-in maintaining gains from diabetes SMAs. In a prior VA efficacy randomized controlled trial, P2P improved VA patients' diabetes-specific social support, insulin starts, and glycemic control compared to usual nurse care management. PROJECT METHODS: P2P program components include at-least weekly telephone calls between paired Veterans with poor diabetes control who are participating in the same SMA group and periodic Veteran-directed group sessions. Participants are matched with another patient of similar age and facing similar self-management challenges. These peer buddies are encouraged to talk by phone at least weekly to provide mutual support and share their progress setting and meeting their self-management goals. The goal is to enhance and help maintain improvements achieved through short-term diabetes self-management training and clinical programs such as diabetes SMAs. Based on the success of separate efficacy trials of diabetes SMAs and of the P2P program, this project will examine the comparative effectiveness of SMAs alone, SMAs + P2P, and usual care without either of these programs and study the implementation process at seven sites in five diverse VA facilities. Outcomes measured at 6- and 12-months post-enrollment include: 1) changes in participants' glycemic and blood pressure control and statin use; 2) service utilization; 3) satisfaction with VA care; 4) diabetes-specific distress; 5) diabetes socia support; and 5) diabetes self- management behaviors. Constructs from the Consolidated Framework for Implementation (CFIR) have already been used in a completed pre-implementation formative evaluation at the study sites that was used to refine the implementation plan at each site. CFIR constructs will also be used during the post- implementation evaluation process to identify recommendations for facilitating widespread dissemination efforts and to contribute to the implementation science literature. Data will be gathered throughout implementation on staff effort required in order to calculate costs of the program.